The precision cleaning of parts to remove contaminants such as waxes, greases, oils and solder flux residues is an integral part of many manufacturing, maintenance, and refurbishing operations. Critically clean parts may be necessary for the next step in the manufacturing process or for satisfactory performance in their end-use application. Many of the solvents, such as 1,1,1-trichloroethane, previously used for these cleaning tasks have been banned or restricted because of toxicological or environmental concerns. Solvent cleaners based on n-propyl bromide meet most of the demands for a new solvent but can be either too aggressive towards some plastic and elastomeric components or not aggressive enough for other applications. For example, when cleaning cellulose triacetate polymer based photographic film in order to remove contaminants such as skin oils and dust, the n-propyl bromide causes film curling such that it must be used in combination with co-solvents. New solvents based on hydrofluorocarbons, hydrofluoroethers, and hydrochlorofluorocarbons are very expensive and are not very efficient as cleaning agents.
The addition of small amounts of no more than about 5% by volume of a fluorine and/or chlorine containing brominated hydrocarbon, such as dibromodifluoromethane, to a flammable organic solvent to provide a fire retardant solvent composition is disclosed in U.S. Pat. No. 5,207,953. A hot vapor stripping process for removing resin coatings from paperstock, which uses an acyclic hydrocarbon containing one to three carbons and two to eight bromine, chlorine or fluorine atoms, at least two of which are bromine or chlorine, is described in U.S. Pat. No. 4,193,838.
We have now found that certain fluorine containing hydrobromocarbon compounds are mild enough to be used neat in cleaning plastic and elastomeric substrates, such as cellulose triacetate polymer based movie film, and yet are effective cleaners for other applications which require a more aggressive cleaning action such as the removal of grease and solder residues from precision metal and electronic parts.